This invention relates to a weft inserting device for a jet loom of the type in which a plurality of main nozzles adapted for inserting weft yarns are respectively associated with the same plurality of supply units supplying said weft yarns. It is the object of the present invention to provide a weft inserting device for a jet loom, according to which a desired one of the main nozzles may be placed at the proper timing in readiness for weft insertion in accordance with a preset weft yarn selecting program.